Digital data insertion apparatus and methods for use with compressed audio/video data

ABSTRACT

Methods and apparatus for inserting data a compressed data bitstream are disclosed. An example method includes inserting audience measurement data in a compressed bitstream by eliminating a first type of data within the compressed data bitstream, packing a second type of data to occupy a location within the compressed data bitstream from which the first type of data is eliminated, and inserting the audience measurement data in a predetermined location within the compressed data bitstream that is expanded as a result of the packing of the second type of data to form a modified compressed data bitstream. The example method also includes generating the ratings information based on the modified compressed data bitstream.

RELATED APPLICATION

This patent is a continuation of U.S. patent application Ser. No.11/237,251, entitled “Digital Data Insertion Apparatus and Methods forUse With Compressed Audio/Video Data,” filed Sep. 8, 2005, which is acontinuation of PCT International Application Serial No.PCT/US2003/028037, entitled “Digital Data Insertion Apparatus andMethods for Use With Compressed Audio/Video Data,” filed Sep. 8, 2003,which claims benefit of U.S. Provisional Patent Application Ser. No.60/420,683, entitled “Digital Data Inserter for Television AudienceMeasurement,” filed on Oct. 23, 2002, which are hereby incorporated byreference in their entireties.

FIELD OF THE DISCLOSURE

The present disclosure relates generally to the delivery anddistribution of compressed digital audio/video content such as digitalbroadcast systems and, more specifically, to digital data insertionapparatus and methods for use with compressed audio/video data.

BACKGROUND

Digital broadcast systems have undergone rapid development anddeployment in recent years due, at least in part, to their ability toefficiently distribute large numbers of high-fidelity video and/or audioprograms, as well as other digital services or programs, over a largegeographic region. For example, in the case of satellite-based digitaltelevision and audio broadcast systems, little, if any, land-basedinfrastructure (e.g., ground stations, cable lines, etc.) is needed toprovide services to subscribers on a world-wide basis. As a result, suchsatellite-based systems enable digital broadcasters and contentproviders to develop markets for their programs and/or services inremote and/or underdeveloped regions of the world in a cost-effectivemanner.

In general, regardless of whether a digital broadcast system uses one ormore satellites, cable transmission lines, ground-based wirelesstransmission stations, or any combination thereof, such a system enablesusers to receive high-fidelity video and/or audio programs, as well asuser-interactive features or tools such as, for example, pictographicprogram guides, grid-based guides, etc. that enable users to plan andcarry out program consumption activities. Digital broadcast systemstypically transmit one or more high-bandwidth signals, each of which istypically composed of a stream of data or data packets having aplurality of video, audio and/or other digital programs or contentmultiplexed therein. A number of well-known data compression techniques(e.g., audio/video content compression techniques), transmissionprotocols and the like are typically employed to generate and transmit amulti-program data stream or bitstream, which is commonly referred to asa transport stream. In particular, digital television programming istypically transmitted according to a standard promulgated by theAdvanced Television Standards Committee (ATSC). The ATSC standard is acomprehensive standard relating to the conveyance of digital televisionsignals. Under the ATSC standard, video information associated with aprogram is encoded and compressed according to the well-known MovingPictures Expert Group-2 (MPEG-2) standard and audio informationassociated with the program is encoded and compressed according to thewell-known AC-3 standard. As a result, an ATSC data stream or bit streamcontains video information in the form of MPEG-2 packets and audioinformation in the form of AC-3 packets. However, other digitaltransmission protocols, data compression schemes and the like may beused instead.

In the case of freely available digital audio/video content orprogramming, users must have a television adapted to receive and processdigital television signals (e.g., a high definition television). In thecase of purchased digital audio/video content or programming,subscribers typically have a digital decoder unit which, in the case ofa digital video or television system, is commonly referred to as a“set-top box,” that receives and processes multi-program data streams ortransport streams and outputs video and audio signals to a television,video monitor, speakers, etc. for consumption by the user. Inparticular, the set-top box can, based on subscriber commands, extractdata packets associated with a particular program or portion ofaudio/video content from a particular data stream or transport stream,decode those extracted data packets and send video and/or audio signalsto a television, video monitor, digital radio, etc. for consumption by auser.

As is the case with analog content providers and broadcasters, digitalcontent providers and broadcasters (e.g., digital televisionbroadcasters, digital audio broadcasters, etc.) often desire to verifythe transmission and/or to meter (i.e., monitor) the consumption of theaudio/video content or programs and/or other services provided tosubscribers. In this manner, a broadcaster can generate broadcastverification information and/or audience program consumption behavior orpatterns. Audience consumption behavior or patterns may be used inconjunction with demographic information to develop ratings information,to improve targeted marketing or advertising campaigns, to improve thetypes of programs or audio/video content and/or services and the timesat which those programs and/or services are delivered to consumers, toassess the value of a particular time slot and program for purposes ofdetermining what advertisers should pay for usage of that time slot,etc.

With known analog television metering systems, viewing records or otherviewing information is typically collected from a group of statisticallyselected households. As with digital broadcast systems, each of thestatistically selected households has a data logging and processing unit(i.e., “home unit” or “site unit”). The site unit is usually coupled toa variety of attachments that provide inputs to the site unit or thatreceive outputs from the site unit. For example, an analog system mayinclude a frequency detector to detect the local oscillator frequency ofa television to identify the channel to which the television iscurrently tuned. Also, for example, a people counter, may be located inthe viewing space of the television and may be in communication with thesite unit, thereby enabling the site unit to actively or passivelydetect the identities of the persons currently viewing programspresented by the television.

The site unit usually processes its inputs, including the inputs fromits attachments, to produce viewing records. The viewing recordstypically contain audio/video content or program identificationinformation (i.e., information that can be used to identify a particularprogram or portion of audio/video content, such as channel informationobtained from the frequency detector) and audience information. Theaudience information may include the numbers and/or identities ofpersons viewing a particular program, demographic information, etc. Theviewing records may be generated on a periodic basis (i.e., at fixedtime intervals) or may be generated in response to a change in an inputsuch as, for example, a change in the identities or number of personsviewing the television, a change in the channel tuning information(i.e., a channel change), etc. With known analog systems, each viewingrecord typically contains channel information such as a station orchannel number and a time (e.g., a date and time of day) at which thechannel was viewed. Of course, viewing records may contain otherinformation such as the identities of viewers present at the viewingtime.

The site unit collects a quantity of viewing records and transmitscollected viewing records, usually daily, to a collection site, such ascentral office or data processing facility, for further processing oranalysis. The data processing facility receives viewing records fromsite units located in some or all of the statistically selectedhouseholds and analyzes the viewing records to ascertain the viewingbehaviors of a particular household or a particular group of householdsselected from all participating households. Additionally, the centraldata processing facility may generate viewing behavior statistics andother parameters indicative of viewing behavior associated with all ofthe participating households.

To generate viewing behavior information from viewing records, thecentral office or data processing facility compares reference data suchas a list of programs (i.e., a schedule of television programming orprogram lineup) to the viewing records. In this manner, the dataprocessing facility can determine which programs were viewed by matchingthe times and channel information in the viewing records to the programsassociated with those same times and channels in the program schedule orlineup. Such a matching process can be carried out for each of theviewing records received by the data processing facility, therebyenabling the data processing facility to reconstruct what programs werewatched by all participating households and the times at which theprograms were watched.

However, known analog program metering systems (such as the televisionprogram verification and metering systems discussed above) are notsuitable for use with digital broadcast systems. For example, thefrequency detector attachment described above is not suitable fordetecting digital video channel information because digital televisionsystems use a data packet extraction process within a set-top box toretrieve audio/video data associated with a particular program, whilethe television tuner is typically allowed to remain on a single channel(e.g., typically channel 2 or 3). As a result, the local oscillatorfrequency of the television tuner is not indicative of (i.e., does notnecessarily correspond to) the digital television channel currentlybeing consumed. Thus, known analog program metering systems are notsuitable for use with digital broadcast systems. More generally, knownanalog program metering systems cannot be used to detect the identity ofbroadcast digital programs, thereby preventing analog monitoring systemsfrom being used to generate verification information and/or viewingrecords that can be processed to determine digital program consumptionbehavior.

To enable the tracking of viewing records, some digital broadcastersenable the identification of digital broadcast programs at home sitesand one or more reference sites by inserting digital programidentification information and/or other data in the video and/or audiobitstream(s). The inserted digital data is commonly referred to asaudience measurement data, which may include signal identification codes(i.e., digital codes that are uniquely associated with respectiveaudio/video content portions or programs), date information, timeinformation, consumer identification information, etc. The insertion ofaudience measurement data at the distribution system headend orbroadcast station is commonly referred to as an active audio/videocontent identification process because the system headend or broadcaststation actively modifies (i.e., inserts data into) the transmittedbitstreams or transport streams.

By actively inserting data into audio/video bitstreams in this manner,digital broadcasters enable the identification of digital audio/videocontent and the viewing behavior of persons viewing digital broadcaststo be readily determined. In particular, the site units associated withindividual homes sites may be configured to extract the insertedaudio/video content identification codes from known portions orlocations within a received bitstream and to use the extractedinformation to form, for example, viewing records. In turn, viewingrecords may be further analyzed at each of the home sites and/or at oneor more collection or central processing sites to generate viewingbehavior information, ratings data, etc.

Typically, known active data insertion techniques insert digital datawithin each of the video and/or audio signals that make up the one ormore programs (i.e., video and/or audio programs) being transmitted bythe broadcast station before the individual video and/or audio signalsare compressed and multiplexed to form a single multi-program bitstreamor transport stream. However, because the digital data are inserted inan uncompressed domain (i.e., within the individual uncompressedaudio/video signals), multiple digital data insertion devices (e.g., onefor each uncompressed program bitstream) are typically required. Thisrequirement for multiple digital information insertion devices isundesirable because it increases the complexity and operational costsassociated with headend or broadcast stations.

Another difficulty that results from inserting digital data intoindividual uncompressed program signals is that subsequent compressionoperations (e.g., compression encoding) may corrupt and/or eliminatesome or all of the inserted data. As is known, signal compressiontechniques usually provide a substantial reduction in the quantity ofdata needed to reproduce a video image and/or an audio signal, but do soat the expense (i.e., the loss) of at least some data or information.Thus, if compression operations corrupt the inserted digital data, thehome site and/or a central data processing or collection facility maynot be able to accurately identify audio/video content.

Still another difficulty that results from inserting digital codes oraudience measurement data into individual uncompressed audio/videocontent signals is that the association between the inserted data orinformation and the program into which the data is inserted is limited.In particular, the inserted data may be associated with only the videoportion of a program or only the audio portion of that same program, butnot both the video and audio portions. This lack of association isfurther complicated by the fact that a digital broadcast station mayredefine the position (e.g., the sub-channel or minor channel number) ofan uncompressed video and/or audio program within the compressed domain,or may delete one or more video and/or audio programs from a programlineup.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of an example system within which the datainsertion apparatus and methods described herein may be used to identifydigital audio/video content or programs and to generate verificationinformation and/or viewing behavior information based on the identifiedaudio/video content or programs.

FIG. 2 is a block diagram of an example known system that may be used bythe digital broadcast station of FIG. 1 to insert audience measurementdata in one or more uncompressed audio/video content or programbitstreams.

FIG. 3 is a block diagram of an example system that may be used withinthe digital broadcast station of FIG. 1 to insert audience measurementdata in a compressed audio/video content or program bitstream.

FIG. 4 is a more detailed block diagram that depicts an example mannerin which the data inserter shown in FIG. 3 may be implemented.

FIG. 5 is a more detailed block diagram depicting an example manner inwhich the data insertion unit of FIG. 4 may be implemented.

FIG. 6 is a block diagram of an example processor-based system thatexecutes software or instructions stored on a machine readable medium toimplement the example data inserter shown in FIG. 3.

FIG. 7 is a flow diagram of an example manner in which the processorsystem shown in FIG. 6 may be configured to perform the functions of theexample data inserter shown in FIG. 3.

FIG. 8 is a more detailed flow diagram of an example manner in which thedata insertion block of FIG. 7 may be implemented.

FIG. 9 is a flow diagram of an example method by which the system shownin FIG. 11 may generate viewing behavior and ratings information usingdata inserted by the example data inserter of FIG. 3.

FIG. 10 is a block diagram of another manner in which a data insertermay be configured to insert audience measurement data in a compressedaudio/video content or program bitstream.

DETAILED DESCRIPTION

FIG. 1 is a block diagram of an example system 100 within which the datainsertion apparatus and methods described in greater detail below may beused to identify broadcast digital audio/video content or programs andto generate viewing behavior and ratings information based on theidentified audio/video content. The system 100 includes a digitalbroadcast station 102 that receives digital video and/or audio contentfrom a plurality of digital content providers 104 and 106. The digitalcontent providers 104 and 106 may provide a variety of audio/videocontent such as, for example, television programs, advertisements, audio(e.g., radio) programs, still image information (e.g., web pages), etc.in known manners to the digital broadcast station 102. The digitalbroadcast station 102 transmits one or more signals containing digitalaudio/video content to a reference site 108 and at least one consumptionsite 110 via communication paths or links 112 and 114. The communicationpaths or links 112 and 114 may include any combination of hardwired orwireless links such as, for example, satellite links, wirelessland-based links, cable links, etc. The signals conveyed via the links112 and 114 may contain multi-program data streams or bitstreams, whichare often referred to as transport streams and commonly employed withexisting digital television transmission systems.

The reference site 108 and the consumption site 110 receive and processthe digital signals or digital audio/video content provided by thedigital broadcast station 102 using the audio/video contentidentification apparatus and methods described herein. Morespecifically, the reference site 108 includes a plurality of decoders(e.g., set-top boxes or the like) 116, 118 and 120 that demodulate,demultiplex and decode audio, video and/or other data packets receivedfrom the digital broadcast station 102. In one example, each of thedecoders 116, 118 and 120 provides audio and/or video data packetsassociated with a different program, which is currently being broadcast,to a reference site processor 122. In other words, the decoder 116 mayprovide data packets associated with a first program while the decoders118 and 120 provide data packets associated with respective second andthird programs. The reference site processor 122 is configured tocontrol and/or has information indicating to which channel, sub-channel,etc. each of the decoders 116, 118 and 120 is currently tuned.

The reference site processor 122 may include apparatus and methods forextracting the data inserted by the digital broadcast station 102 intothe broadcast audio/video content (e.g., one or more transport streams).In particular, the reference site processor 122 may be configured toextract digital codes and/or other data or information inserted by thedigital broadcast station 102 from known locations within data packetsand/or data frames using the data insertion apparatus and methodsdisclosed herein. The reference site processor 122 may send theextracted codes and/or other digital information to a central processingunit 124 that, in turn, may process the extracted codes and/or otherdigital information to generate, for example, broadcast verificationinformation, program lineup information, or any other desiredinformation relating to the audio/video content broadcast by the station102.

The consumption site 110 could be, for example, a statistically selectedhome or residence, a business location, a mobile device (e.g., aportable computer, cellular phone or personal data assistant, etc.) orany other site or device enabling the consumption of video and/or audiocontent or programs. For purposes of simplifying the discussion, FIG. 1depicts a single system or consumption site 110. However, a plurality ofconsumption sites may be configured in manners similar or identical tothat of the example consumption site 110.

The consumption site 110 includes an output unit 128 such as, forexample, a video display, television, speaker, etc. The consumption site110 also includes a decoder (e.g., a set-top box) 130, which may besimilar or identical to the decoders 116-120. As shown in FIG. 1, thedecoder 130 may be serially interposed between the broadcast signal 114and the output unit 128 and provides audio and/or video signals 134 tothe output unit 128 that are used to present the program currentlyselected for consumption. For example, in the case where the broadcastsignal 114 is a digital satellite or cable television transmission, thedecoder 130 demodulates extracts video and/or audio data packetsassociated with a desired channel and/or program. The extracted datapackets are processed to form the signal 134 that can be presented(e.g., displayed) by the output unit 128. For example, in the case wherethe output unit 128 is a television, the signal 134 may be a compositevideo signal, a super-video signal, a red, green, blue (RGB) signal, orany other displayable video signal applied to the appropriate inputconnections of the output unit 128.

In addition, the decoder 130 also provides signals 136 containingdigital audio/video content data to the site unit 132. The audio/videocontent data may, for example, be digital audio signals provided usingthe well-known Sony Corporation and Philips Corporation DigitalInterface Format (S/PDIF), or any other desired format that providesdata packets associated with digital broadcasts. In that case, theaudio/video content data is compressed digital audio data associatedwith audio/video content to which the decoder is currently tuned andwhich is being consumed via the output unit 128.

In addition to its signal processing functions, the decoder 130 may alsoperform access control functions such as, for example, determining whatprograms are available for consumption by a user of the system 100 basedon subscription status or subscription information associated with thesystem 100, generating displayable program guide information, etc.

The site unit 132 processes the signals 136 received from the decoder130 to extract the inserted data (e.g., audience measurement data)therefrom. The site unit 132 may then convey the extracted digital data(e.g., audience measurement data) to the central processing unit 124.The central processing unit 124 may process the extracted digital datato determine what audio/video content (e.g., channels and/or programs)was consumed, the times at which the audio/video content was consumed,and/or the identities of those who consumed the audio/video content. Inthis manner, the central processing unit 124 may generate viewingbehavior information or statistics, ratings information or any otherdesired information relating to the consumption of audio/video contentat the consumption site 110 or at one or more other consumption sites(none of which are shown).

While the output unit 128, the decoder 130 and the site unit 132 aredepicted in FIG. 1 as separate blocks, the functions performed by theseblocks may be combined or integrated in any desired manner. For example,in the case where the consumption site 110 is a portable device (e.g., apersonal data assistant having a wireless communication interface), thefunctions performed by the blocks 128, 130 and 132 may be integratedwithin the portable device. Alternatively, the functions performed bythe output unit 128 and the decoder 130 may be integrated within theportable device, which is then periodically or continuouslycommunicatively coupled to the site unit 132 to download its extracteddata to the site unit 132. In that case, the site unit 132 may beimplemented as a base unit in which the portable device is periodicallydisposed to perform download operations.

FIG. 2 is a block diagram of an example known system 200 that may beused by the digital broadcast station 102 of FIG. 1 to insert audiencemeasurement data into one or more uncompressed audio/video content orprogram bitstreams. The system includes a plurality of data inserters202, 204 and 206, each of which is configured to insert data intorespective uncompressed audio/video content data streams 208, 210 and212. Each of the streams 208, 210 and 212 contains a single audio/videoprogram, which may be provided by a digital content provider similar oridentical to the digital content providers 104 and 106 shown in FIG. 1and/or which may be provided a local source such as, for example, adigital video recorder, a video cassette recorder, or any other suitabledigital media delivery devices.

The data inserters 202, 204 and 206 may be implemented using known datainsertion devices such as vertical blanking inserters, watermarkingencoders and closed caption encoders. The outputs of the data inserters202, 204 and 206 are coupled to respective encoders 214, 216 and 218.The encoders 214, 216 and 218 are compression encoders that compresseach of the individual audio/video content bitstreams (into which datahas been inserted) using a known audio/video compression scheme such asfor example, a compression scheme compliant with the AC-3 and/or MPEGstandards.

The compressed audio/video content bitstreams output by the encoders214, 216 and 218 are multiplexed to form a single bitstream or transportstream by a multiplexer 220. The multiplexer 220 may multiplex thecompressed bitstreams received from the encoders 214, 216 and 218 usinga multiplexing scheme compliant with, for example, the ATSC and/orDigital Video Broadcast (DVB) standards. The multiplexer 220 providesits multi-program bitstream or transport stream to a modulator 222,which modulates the transport stream using known techniques, and atransmitter 224, which uses known techniques to transmit or broadcastthe transport stream via, for example, the communication links 112 and114 shown in FIG. 1.

The system 200 may also include a Program and System InformationProtocol (PSIP) generator 226, which uses well known techniques togenerate a collection of hierarchically interlinked tables that containinformation relating to the location of channels and programs, programscheduling (e.g., program lineup information), information facilitatingthe construction of program guides, as well as unique identifiers suchas transport stream identifiers (TSIDs), each of which uniquelycorresponds to a broadcaster. The PSIP generator 226 provides the PSIPinformation to the multiplexer 220, which multiplexes the PSIPinformation into the transport stream.

In addition, the system 200 may include a data generator 228, which mayprovide interactive program information to the multiplexer 220, whichmultiplexes the interactive program information into the transportstream. For example, the data generator 228 may generate programinformation that may be used at a consumption site (e.g., theconsumption site 110 shown in FIG. 1) to generate a program grid-guideand/or to provide other user interface functionality at the consumptionsite.

While the known system 200 of FIG. 1 enables audience measurement datato be inserted into individual audio/video program bitstreams, theinserted data may be corrupted or lost during the encoding orcompression process performed by each of the encoders 214, 216 and 218.In addition, because the data inserters 202, 204 and 206 insert audiencemeasurement data without reference to the information being generated bythe PSIP generator 226, changes in program lineup (e.g., reassignment ofa program by a station to a different sub-channel, removal of a program,etc.) are not considered during the data insertion process. As a result,the inserted audience measurement data extracted at a consumption sitemay not reflect the programs or audio/video content actually consumed.To address this issue, two sets of metadata would have to be maintainedto generate ratings information. In particular, one set of metadataassociated with the inserted data and another set of metadata generatedby the PSIP device (e.g., station or broadcaster metadata that is usedfor program identification). In addition, a mapping between the two setsof metadata would be required so that ratings information couldultimately be provided in terms the metadata generated by the PSIPdevice. Still further, the system 200 requires a separate data inserterfor each program bitstream and, thus, may become overly complex in caseswhere the broadcast station (e.g., the broadcast station 102 of FIG. 1)multiplexes a large number of programs to form its transport stream orif a new channel is introduced for transmission.

FIG. 3 is a block diagram of an example system 300 that may be usedwithin the digital broadcast station 102 of FIG. 1 to insert audiencemeasurement data in a compressed audio/video content or programbitstream. Many of the functional blocks shown in the system 300 of FIG.3 are similar or identical to those shown and described in connectionwith FIG. 2. However, the system 300 interposes a data inserter 302between the multiplexer 220 and the modulator 222, thereby eliminatingthe need for the plurality of data inserters 202, 204 and 206 (FIG. 2).In contrast to the data inserters 202, 204 and 206, the data inserter302 operates in a compressed domain. In particular, the data inserter302 inserts data (e.g., audience measurement data and/or other data) ina multi-program bitstream or transport stream that contains compressedaudio/video data, PSIP information generated by the PSIP generator 226and/or other data generated by the data generator 228.

As described in greater detail below, the data inserter 302 operates ona bitstream containing frames of data packets that are formatted using apredefined compression and transmission protocol. The data inserter 302temporally packs or time shifts data within data frames to expand (i.e.,increase the size of) a predetermined data area or location within oneor more of the data frames and inserts audience measurement data withinthe one or more expanded predetermined data areas or locations. Theinserted audience measurement data may then be extracted by one or moredecoders at one or more consumption sites and reference sites and usedto generate consumption records, verification information, programlineup information, viewing behavior information etc.

Because the data inserter 302 operates in a compressed domain (i.e., itoperates on bitstreams containing compressed data), the audiencemeasurement data that it inserts cannot be corrupted or lost as a resultof compression operations, as is the case with known systems (e.g., theknown system 200 shown and described in connection with FIG. 2). Inaddition, because the data inserter 302 has access to the informationgenerated by the PSIP generator 226, the data inserter 302 alwaysinserts audience measurement data that is consistent with the programlineup information contained with the PSIP tables provided by the PSIPgenerator 226. In this manner, the system 300 maintains two metadatasystems (i.e., the metadata produced by the PSIP device and the metadataproduced as a result of the data insertion process) that contain thesame information. As a result, the system 300 provides audiencemeasurement data that is more reliable than that provided by the knownsystem 200 of FIG. 2, particularly in cases where the broadcast station102 (FIG. 1) makes frequent changes to its program lineup.

The system 300 may also include a data generator 304 that generatesnon-audience measurement data such as, for example, interactive data(e.g., uniform resource locators (URLs), Internet protocol (IP) data,etc.), private or proprietary data, or any other non-audiencemeasurement data. In one example, the data generator 304 may generatedata using the format shown below.

Time Code: XX

Minor Channel/Major Channel: XX/YY

Data: http://xx.xx.xxx

The data generator 304 may be separate from the data inserter 302 asshown in FIG. 3, in which case the data generator 304 may becommunicatively coupled to the data inserter 302 via a communicationlink 306 such as for example, a serial interface, an Ethernet compatiblelink, or any other suitable communication link. Alternatively, the datagenerator 304 may be integral with the data inserter 302. The datagenerator 304 may also be coupled to a user interface 306, which mayinclude a keyboard, monitor, mouse, etc. that enable an operator toenter data to be inserted via the data generator 304 and the datainserter 302.

Now turning to FIG. 4, a more detailed block diagram depicts an examplemanner in which the data inserter 302 shown in FIG. 3 may beimplemented. The example data inserter 302 includes a demultiplexer 400that receives a multi-program bitstream (e.g., an ATSC compliant datastream) from the multiplexer 220 (FIG. 3). The demultiplexer 400separates the multi-program bitstream into a plurality of bitstreams,including bitstreams containing compressed data associated withindividual audio/video programs, a bitstream containing PSIPinformation, a bitstream containing data generated by the data generator228, etc.

A program information extractor 402 receives the individual bitstreamsoutput by the demultiplexer 400 and extracts program informationtherefrom. In particular, the program information extractor 402 mayextract a transport stream identifier, which uniquely corresponds to thebroadcasting source (e.g., the station 102 of FIG. 1) from which themulti-program bitstream was transmitted, major and minor channelinformation for each of the bitstreams corresponding to an audio/videoprogram, date and time values for each of the audio/video programbitstreams, as well as any other desired program information.

The audience measurement data generator 404 uses the extracted programinformation provided by the program information extractor 402 togenerate audience measurement data for each of the audio/video programbitstreams contained within the multi-program bitstream received by thedemultiplexer 400. The audience measurement data generator 404 maygenerate audience measurement data using the example syntax set forth inTable 1 below.

TABLE 1 Data Field Length in bits AudienceMeasurementDataID 8PayloadStartIndex 4 LenIndex 4 Payload Variable

The data field AudienceMeasurementDataID contains a unique identifierthat may be used by decoders (e.g., the decoders 116, 118, 120, and 130)to identify audience measurement data and/or the audience measuremententity (e.g., a company) that has inserted the data. Such uniqueidentifiers may be known in advance to facilitate the identificationprocess. The data field PayloadStartIndex holds a value indicating theorder in which audience measurement information is stored in thepayload. One example manner in which the values of PayloadStartIndex maycorrespond to payload data organization is set forth in Table 2 below.

TABLE 2 PayloadStartIndex Payload Data Starts With 0 TransportID [bit15-0] 1 Major channel [bit 15-0] 2 Minor channel [bit 15-0] 3 Time [bit31-16] 4 Time [bit 15-0]

The data field LenIndex holds a value that indicates the length of thedata field Payload. One example manner in which the data field LenIndexmay define the length of the data field Payload in set forth in Table 3below.

TABLE 3 LenIndex Payload Length in Bytes 0 2 1 4 2 6 3 8 4 10

Using the above example data field semantics set forth in Tables 1through 3, if PayloadStartIndex=3 and LenIndex=3, then the payloadcontains eight bytes in the order set forth in Table 4 below. Thus, theLenIndex data field enables modulation of the length of the insertedaudience measurement data as a function of the number of bytes availablein the inserted data location or placeholder.

TABLE 4 Payload Data No. of Bytes Time [bit 31-16] 2 Time [bit 15-0] 2Transport ID [bit 15-0] 2 Major Channel [bit 15-0] 2

Of course, Tables 1 through 4 above are merely one example manner inwhich the audience measurement data generator 404 may generate audiencemeasurement data. Other data types and formats may be used to formaudience measurement data for any desired application. For example, theTransport ID may be replaced by a proprietary identifier that is usedby, for example, an audience measurement entity (e.g., a company) toidentify a channel with a particular major/minor channel number.Alternatively, the Transport ID may be replaced with a public contentidentifier such as, for example, an AD-ID or V-ISAN, which are wellknown content identification schemes.

A data insertion unit 406 inserts the audience measurement data providedby the audience measurement data generator 404 in the individualbitstreams, which correspond to the individual audio/video programsprovided by the demultiplexer 400. More specifically, the data insertionunit 406 packs or time shifts compressed data packets within the dataframes of each audio/video program bitstream to expand a predeterminedportion or data area of one or more data frames within those compresseddata bitstreams. Audience measurement data pertaining to each of thoseaudio/video bitstreams is inserted into one or more of the expandedpredetermined portions or data areas.

In addition to receiving audience measurement data to insert, the datainsertion unit 406 may also receive other data such as, for example,non-audience measurement data to insert from the data generator 304(FIG. 3). As described above, such non-audience measurement data mayinclude interactive data such, for example URLs, applets, scripts, etc.Example syntax for such non-audience measurement data is set forth belowin Tables 5 and 6.

TABLE 5 Data Field Value/Length Interactive Data Identifier 0xBB H DataLength XX bytes Data Type YY Data ZZ

TABLE 6 Data Type Value Data Type Description 0 URL 1 Scripts 2 Applets

Audio/video bitstreams having data inserted therein by the datainsertion unit 406 are provided to the program information modifier 408,which may, if needed, modify the program information associated with oneor more of those bitstreams. In some cases, depending on where in thebitstream the data insertion unit 406 inserts the audience measurementdata or other data, the program information associated with thebitstream into which the data has been inserted may have to be updated.For example, in the case where the program information includes PSIPand/or PSI table information, it may be necessary to modify theinformation the PSIP and/or PSI table information to reflect changes toreflect that private data has been inserted in the bitstream.

After being processed by the program information modifier 408, amultiplexer 410 receives the individual bitstreams, includingaudio/video bitstreams into which audience measurement data and/or otherdata has been inserted by the data insertion unit 406. The multiplexer410 also receives program information, which may have been modified viathe program information modifier 408. For example, the multiplexer 410may receive bitstreams containing modified PSIP information. Still otherbitstreams may be received by the multiplexer 410 such as, for example,a bitstream containing other programs or data. In any event, themultiplexer 410 multiplexes the plurality of bitstreams that it receivesinto a single multi-program bitstream or transport stream that may havesubstantially the same format (e.g., that is compliant with the sameprotocol) as the transport stream received by the demultiplexer 400.However, the multi-program bitstream or transport stream output by themultiplexer 410 contains data inserted by the data insertion unit 406and may contain program information modified by the program informationmodifier 408.

FIG. 5 is a more detailed block diagram depicting an example manner inwhich the data insertion unit 406 may be implemented. The data insertionunit 406 may include a parser 500 that parses out or extracts aparticular type or types of data packets to be passed to a time shifter502. In one example, where data insertion unit 406 is implemented withinthe digital broadcast station 102 of FIG. 1 and where the digitalbroadcast station 102 is configured to transmit ATSC compliant digitaltelevision signals, the parser 500 is configured to extract compressedaudio data packets compliant with the AC-3 standard. In that example,the time shifter 502 is configured to time shift the compressed audiodata packets within AC-3 data frames to reduce the number of or toeliminate skip bytes within the AC-3 data frames.

As is well known, compressed audio bitstreams compliant with the AC-3standard typically include frames having one or more skip bytes, whichare formed during the encoding process to maintain a fixed frame sizefor each AC-3 frame and which typically do not contain any usefulinformation. In addition, AC-3 data frames contain an auxiliary datafield, which may be used to transmit information other than compressedaudio data and/or may be used to fine tune the number of bits containedin a frame. However, in practice, the auxiliary data fields within AC-3frames typically include few, if any, bytes.

As noted above, the time shifter 502 reduces the number of or eliminatesskip bytes within AC-3 frames and shifts audio data within the AC-3frames to occupy the eliminated skip bytes. The result of the shiftingis a packing of the compressed audio data toward one end of the framesto occupy portions of the frames previously occupied by skip bytes,which effectively temporally shifts the audio data. Another result ofthis shifting is an increase in the number of bits available for theauxiliary data fields.

An auxiliary data field inserter 504 inserts the audience measurementdata generated by the audience measurement data generator 404 into thenewly expanded auxiliary data fields of the AC-3 frames. The insertedaudience measurement data may be formatted as described above inconnection with Tables 1 through 4 above, or in any other desiredmanner. Alternatively or additionally, non-audience measurement dataprovided by the data generator 304 (FIG. 3) may be inserted in theauxiliary data fields of the AC-3 frames by the auxiliary data fieldinserter 504.

After the audience measurement data and/or other data has been insertedin the newly expanded auxiliary data field of the AC-3 frames, an errorchecking value generator 506 generates new error checking values foreach AC-3 frame. In this example, the error checking value generator 506is configured to re-compute the cyclical redundancy check (CRC) values,which represent within each AC-3 frame. Re-computation of the CRC valuesfor the AC-3 frames is necessary because elimination of skip bytes,shifting compressed audio data and inserting data in the AC-3 frameauxiliary data fields renders the original CRC values meaningless (i.e.,the original CRCs are no longer representative of the data contained inthe frames).

In general, the example data inserter 302 (FIG. 3) and data generator304 (FIG. 3) may be implemented using primarily hardware, primarilysoftware or any desired combination of hardware and software. In thecase of a primarily software-based implementation, a computer system orother processor system that executes machine readable instructions orprograms may be used to implement the apparatus and methods describedherein. The machine readable instructions or programs may be embodied insoftware stored on a tangible medium such as a CD-ROM, a floppy disk, ahard drive, a digital versatile disk (DVD), or a memory.

FIG. 6 is a block diagram of an example processor-based system 600 thatexecutes software or instructions stored on a machine readable medium toimplement the example data inserter 302 (FIG. 3) and/or the example datagenerator 304 (FIG. 3). The example processor-based system 600 includesa processor 602, which may be any suitable microprocessor such as, forexample, a processor from the Intel Pentium® family of microprocessors.The processor 602 is communicatively coupled to a non-volatile memory604 and a volatile memory 606. The non-volatile memory 604 may beimplemented using, for example, electrically erasable programmable readonly memory (EEPROM), read only memory (ROM), etc. The volatile memory606 may be implemented using, for example, static random access memory(SRAM), dynamic random access memory (DRAM), etc. The processor 602 isalso coupled to a mass storage device 608, which may be implementedusing, for example, a disk drive that stores digital information using amagnetic or optical media.

The processor 602 retrieves and executes machine readable instructionsor software programs that are stored on one or more of the memories 604and 606 and/or the mass storage device 608 to perform the functions ofthe data inserter 302 and/or data generator 304 shown in FIG. 3.

The processor 602 is also in communication with an input/output (I/O)unit 610, that enables the system 600 to communicate with, for example,the user interface 308 (FIG. 3). The I/O unit 610 may include circuitryfor performing network communication functions (e.g., Ethernetcommunication functions), phone line communication functions (e.g.,modem functions), peripheral device communication functions (e.g.,universal serial bus communications, parallel port communications, etc.)to enable the system 600 to communicate with one or more input devicessuch as, for example, a mouse, keyboard, etc. and/or one or more outputdevices such as, for example, a video display, a printer, etc.

FIG. 7 is a flow diagram of an example manner in which the processorsystem 600 shown in FIG. 6 may be configured to perform the functions ofthe data inserter 302 shown in FIG. 3. Initially, the multi-programbitstream or transport stream received from the multiplexer 220 (FIG. 3)is demultiplexed into its constituent bitstreams (block 700). Inparticular, the transport stream may be separated into a plurality ofaudio/video program bitstreams, a bitstream containing PSIP information,as well as other bitstreams containing other data and/or programinformation. Program information such as, for example, transport streamidentifiers, major and minor channel numbers, date and time value, etc.are then extracted from the constituent bitstreams (block 702). Theextracted program information is then used to generate audiencemeasurement data (block 704), which is subsequently inserted inpredetermined portions or data fields within the audio/video bitstreams(block 706). The program information may then be modified, if necessary,(block 708) and the constituent bitstreams, some of which have beenmodified via insertion of audience measurement data and/or modificationof program information, are multiplexed to form a single transportstream (block 710).

FIG. 8 is a more detailed flow diagram of an example manner in which thedata insertion block 706 of FIG. 7 may be implemented. In particular,the audio/video bitstreams are parsed to extract certain data packetsinto which data will be inserted. In one example, as described above,audio data packets compliant with the AC-3 standard are extracted. Theaudio data within the AC-3 data frames is time shifted to eliminate skipbytes within the frames (block 802), thereby increasing the number ofbits available to the auxiliary data field within one or more of thedata frames. Audience measurement data, as well as other data, may thenbe inserted in the newly expanded auxiliary data field (block 804). TheCRC for each AC-3 frame is then re-computed (block 806).

FIG. 9 is a flow diagram of an example method by which the system 100shown in FIG. 1 may generate viewing behavior and ratings informationusing data inserted by the data inserter 302 of FIG. 3. Initially, thedigital broadcast station 102 (FIG. 1) inserts audience measurement datainto its broadcast transport stream using, for example, the datainserter apparatus and methods described herein (block 900). One or moreof the decoders 116, 118 and 120 (FIG. 1) together with the referencesite processor 122 (FIG. 1) extract the audience measurement data fromknown locations within the transmitted bitstreams (block 902). Forexample, in the case where the data inserted within the compressed audiobitstreams compliant with the AC-3, the known locations may be theauxiliary data fields of the AC-3 frames as described above. Thereference site processor 122 (FIG. 1) uses the extracted audiencemeasurement data to generate a program lineup (block 904). Inparticular, because the reference site 108 (FIG. 1) can use its multipledecoders 116, 118 and 120 to receive and process multiple audio/videobitstreams simultaneously, the reference site processor 122 (FIG. 1) cansimultaneously detect and identify, using the inserted audiencemeasurement data, a plurality of broadcast programs available forconsumption. The reference site 122 (FIG. 1) may then transmit thegenerated program lineup information to the collection site (block 906),which in this case is the central processing facility 124 (FIG. 1).

At the consumption site 110 (FIG. 1), the site unit 132 is configured toextract the inserted audience measurement data from the signal 136(block 908), which, in one example, is an S/PDIF signal containingcompressed audio data compliant with the AC-3 standard. In that case,the inserted audience measurement data is located in the auxiliary datafields of the AC-3 data frames and the site unit 132 (FIG. 1) isconfigured to identify the auxiliary data fields and to extractinformation therefrom. The site unit 132 (FIG. 1) is also coupled to apeople meter and/or other devices that enable the site unit 132 (FIG. 1)to generate demographic information (block 910). For example, the siteunit 132 (FIG. 1) may be configured to detect the identities of theperson or persons currently consuming an audio/video program via theoutput unit 128. In any event, the site unit 132 (FIG. 1) transmits theviewing behavior information (i.e., the audience measurement data,demographic information, etc.) to the collection site (block 912) (i.e.,the central processing facility 124 (FIG. 1)).

The collection site or central processing facility 124 (FIG. 1) thencompares the viewing behavior information received from the consumptionsite 110 (FIG. 1) to the program lineup information received from thereference site 108 (FIG. 1) (block 914). By matching the viewingbehavior information to portions of the program lineup information, thecollection site or central processing facility 124 (FIG. 1) maydetermine the time and manner in which audio/video programs wereconsumed at the consumption site 110 (FIG. 1) and/or other consumptionsites (not shown) and by whom those audio/video programs were consumed.The matching information generated at block 914 may then be used by thecentral processing facility 124 (FIG. 1) to generate ratings information(block 916).

In cases where the data generator 304 (FIG. 3) has provided non-audiencemeasurement data (e.g., interactive data) to the data inserter 302 (FIG.3), the decoder 130 (FIG. 3) and/or site unit 132 (FIG. 3) may extractfrom the auxiliary data fields of the AC-3 frames and process thatnon-audience measurement data. For example, the site unit 132 (FIG. 1)may include or be coupled to a web server (not shown) that enablesactivation of URLs and/or other interactive data. In some cases, thenon-audience measurement data may be appropriately transcoded andconveyed via one or more wireless communication links to a portabledevices such as, for example, a cellular phone, personal data assistantand/or a computer.

Although the example data inserter 302 is depicted in FIG. 3 as beingserially interposed between the multiplexer 220 and the modulator 222,other configurations may be used instead to achieve results identical orsimilar to those described above. FIG. 10 is a block diagram of anothermanner in which a data inserter 1000 may be configured to insertaudience measurement data in a compressed audio/video content or programbitstream. As depicted in FIG. 10, the data inserter 1000 iscommunicatively coupled to the PSIP generator 226, one or more of theencoders 208, 210 and 212 and the multiplexer 220. In thisconfiguration, the data inserter 1000 does not require a demultiplexer(e.g., the demultiplexer 400 of FIG. 4) or a multiplexer (e.g. themultiplexer 410 of FIG. 4). Still other configurations are possible. Forexample, the data inserter 1000 may be integrated with the PSIPgenerator 226 and/or one of more of the encoders 208-212.

While the data insertion apparatus and methods described herein havebeen described with reference to specific examples, the apparatus andmethods may be implemented in different manners to achieve identical orsimilar results. More specifically, although example methods andapparatus may time shift compressed audio data within AC-C compliantdata frames to expand the number of bits available for AC-3 frameauxiliary data fields, into which data may be inserted, other insertiontechniques may be used instead. For example, audience measurement dataand/or other data may be inserted in private descriptors such as, forexample, the ATSC private descriptor, the MPEG-2 metadata descriptorand/or the MPEG-2 private descriptor in Program System Information (PSI)tables (e.g., the program loop that is present in a program map table(PMT) section). Alternatively or additionally, the audience measurementdata and/or other data may be inserted in Event Information Tables(EITs), A-90 data packets and/or null or padding packets to achieveidentical or similar results.

Although certain methods, apparatus and articles of manufacture havebeen described herein, the scope of coverage of this patent is notlimited thereto. To the contrary, this patent covers all embodimentsincluding apparatus, methods and articles of manufacture fairly fallingwithin the scope of the appended claims either literally or under thedoctrine of equivalents.

What is claimed is:
 1. A method of generating ratings information, themethod comprising: inserting audience measurement data in a compressedbitstream by: eliminating a first type of data within the compresseddata bitstream; packing a second type of data to occupy a locationwithin the compressed data bitstream from which the first type of datais eliminated; and inserting the audience measurement data in apredetermined location within the compressed data bitstream that isexpanded as a result of the packing of the second type of data to form amodified compressed data bitstream; and generating the ratingsinformation based on the modified compressed data bitstream.
 2. A methodas defined in claim 1, wherein generating the ratings information basedon the modified compressed data bitstream includes: generating programlineup information based on audience measurement data extracted at afirst location; generating consumption information based on audiencemeasurement data at a second location; and comparing the program lineupinformation to the consumption information to generate the ratingsinformation.
 3. A method as defined in claim 1, wherein the compresseddata bitstream includes at least an audio program or a video program. 4.A method as defined in claim 1, wherein the first type of data includesa skip byte and the predetermined location is an auxiliary data field.5. A method as defined in claim 1, wherein the second type of dataincludes compressed audio content or compressed video content.
 6. Amethod as defined in claim 1, wherein the compressed data bitstream isAC-3 compliant.
 7. A method as defined in claim 6, further includingre-computing cyclical redundancy check values for each AC-3 frame of thecompressed data bitstream after inserting the audience measurement datain the predetermined location.
 8. A system for generating ratingsinformation, the system comprising: a memory; and a processor coupled tothe memory, the processor to: insert audience measurement data in acompressed bitstream by: eliminating a first type of data within thecompressed data bitstream; packing a second type of data to occupy alocation within the compressed data bitstream from which the first typeof data is eliminated; and inserting the audience measurement data in apredetermined location within the compressed data bitstream that isexpanded as a result of the packing of the second type of data to form amodified compressed data bitstream; and generate the ratings informationbased on the modified compressed data bitstream.
 9. A system as definedin claim 8, wherein the processor is to generate the ratings informationbased on the modified compressed data bitstream by: generating programlineup information based on audience measurement data extracted at afirst location; generating consumption information based on audiencemeasurement data at a second location; and comparing the program lineupinformation to the consumption information to generate the ratingsinformation.
 10. A system as defined in claim 8, wherein the compresseddata bitstream includes at least an audio program or a video program.11. A system as defined in claim 8, wherein the first type of dataincludes a skip byte and the predetermined location is an auxiliary datafield.
 12. A system as defined in claim 8, wherein the second type ofdata includes compressed audio content or compressed video content. 13.A system as defined in claim 8, wherein the compressed data bitstream isAC-3 compliant.
 14. A system as defined in claim 13, wherein theprocessor is to re-compute cyclical redundancy check values for eachAC-3 frame of the compressed data bitstream after inserting the audiencemeasurement data in the predetermined location.
 15. A machine readablestorage device or storage disk comprising instructions that, whenexecuted, cause a machine to at least: insert audience measurement datain a compressed bitstream by: eliminating a first type of data withinthe compressed data bitstream; packing a second type of data to occupy alocation within the compressed data bitstream from which the first typeof data is eliminated; and inserting the audience measurement data in apredetermined location within the compressed data bitstream that isexpanded as a result of the packing of the second type of data to form amodified compressed data bitstream; and generate the ratings informationbased on the modified compressed data bitstream.
 16. A machine readablestorage device or storage disk as defined in claim 15, wherein theinstructions, when executed, cause the machine to generate the ratingsinformation based on the modified compressed data bitstream by:generating program lineup information based on audience measurement dataextracted at a first location; generating consumption information basedon audience measurement data at a second location; and comparing theprogram lineup information to the consumption information to generatethe ratings information.
 17. A machine readable storage device orstorage disk as defined in claim 15, wherein the compressed databitstream includes at least an audio program or a video program.
 18. Amachine readable storage device or storage disk as defined in claim 15,wherein the first type of data includes a skip byte, the second type ofdata includes compressed audio content or compressed video content andthe predetermined location is an auxiliary data field.
 19. A machinereadable storage device or storage disk as defined in claim 15, whereinthe compressed data bitstream is AC-3 compliant.
 20. A machine readablestorage device or storage disk as defined in claim 19, wherein theinstructions, when executed, cause the machine to re-compute cyclicalredundancy check values for each AC-3 frame of the compressed databitstream after inserting the audience measurement data in thepredetermined location.